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Secure heavy water tanks

Unsecured hot water cylinders and header tanks can cause damage or injury if they move or fall in an earthquake. Most people can secure a water tank without needing professional help.

Prevent leaks and damage from heavy water tanks

Your hot water cylinder is heavy and can contain hundreds of litres of hot water. If it tips over in an earthquake it can cause serious damage due to its size and weight. If water or gas pipes connected to the cylinder come loose, they can leak water and gas into your home.

Header tanks are usually found in older homes and will either be in the roof space, or on the roof. Even if its empty, a concrete header tank can weigh a lot. If the tank moves in a quake, it can fall through or off the roof – posing a risk of damage and injury.

A secure water cylinder and header tank increases the chance of keeping the plumbing connections intact – so your whānau can stay safe and use the water after an earthquake.

Check your hot water cylinder

Most of the time your hot water cylinder will be in a cupboard. Look to see if your cylinder is fixed to the house’s structure.

Check the:

  • metal strapping around the cylinder is sufficient, for example at the top and bottom of the cylinder and correctly positioned
  • wooden blocking is anchored to wall studs.

If you don’t see straps and blocking, your cylinder is not secure. To secure it, either contact a building professional, or do it yourself using the instructions below.

Homes built after 1992 are required to have secured cylinders to comply with the Building Code. Even if you’re in a newer home, you should still check to see if your cylinder is correctly secured. 

Secure a hot water cylinder yourself

If you're confident doing DIY, securing a hot water cylinder is probably a job you can take on yourself, and the equipment costs under $50.

If you know someone who might struggle with this job, you could give them a hand. If you'd like help, get in touch with a builder or plumber.

Hot water cylinders should be secured with blocks of wood (blocking) and steel restraining straps to stop the cylinder from rocking and tipping in an earthquake.

How water cylinder with strapping across the front. Cylinders that are 200 litres or smaller require two steel restraining straps. Extra straps are required if your cylinder is:

  • larger than 200 litres
  • located more than 12 metres above finished ground level
  • unable to have straps positioned within 10cm of the top and bottom of the cylinder.

What you'll need

  • Stud finder
  • A power drill
  • 2x lengths of 50x50mm timber blocking that are the same height as the cylinder
  • A cylinder restraint kit that includes 25×1 mm galvanised steel straps, screws, and washers – purchase from your local hardware store.

Installing the restraints

Attach timber blocking

  1. Cut and fit two vertical 50x50mm timber blocks up the full length of the cylinder.
  2. Attach the blocks to the wall studs and make sure they fit snugly between the wall and the cylinder or heater. A stud finder can be a helpful tool when locating wall studs.

Add the steel strapping

  1. Work out how many straps you need, depending on the size and location of your hot water cylinder. You’ll need at least three straps if your cylinder is larger than 200 litres.
  2. Decide where the straps will be fastened. They should be positioned within 10cm of the top and bottom of the cylinder, and away from the water inlet and plumbing controls.
  3. Screw the steel straps into a wall stud – you can use a stud finder to check. If there is no stud in the right place, fix a short piece of timber horizontally across two wall studs to give you something solid to attach the steel straps to.
  4. Attach the galvanised steel straps securely with screws into the wall stud.
  5. Use the tensioning device that comes with the steel straps to tighten the steel strap.
  6. Once all the straps are screwed and tightened, test the hot water cylinder is secure by gently rocking it. It should feel firm and only move slightly.
  7. Double check there is no strain on the water inlet pipes.
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Check your header tank is secure

Header tanks feed water into a hot water cylinder, and are located in the attic, roof space, or on the roof.

Header tank with strapping over it. Similar to your hot water cylinder – you should have a look to see if you have a header tank, and whether it’s secure. Look for strapping over the tank, with timber blocking anchored to the ceiling joists.

If you don’t see straps or blocking, your tank is not secure and could cause damage if it moves in earthquake shaking. The safest option is to completely remove your header tank if it’s not in use. Talk to a licensed building practitioner about the best way to do this.

If your tank is in use, talk to a licensed plumber about installing flexible fittings between your tank and its supply lines.

How to restrain your header tank

You can restrain your existing tank yourself or get a licensed building practitioner to do it for you.

What you'll need

  • Timber blocking
  • A power drill
  • Tie-down straps

Follow these instructions:

  1. Securely nail wooden blocks at four locations around the perimeter of the tank’s tray and fit wooden blocks between the tray and the tank.
  2. Place tiedown straps across the tank to secure it to the roof framing.

Turning off water mains after a quake

You've now reduced the risk of your cylinder breaking away from its water or gas lines. But in an earthquake, there's a risk those services could rupture in other places.

As an important safety measure, know how to turn off your water and gas mains as quickly as you can after a quake.

Next steps

Secure other furniture

Protect your home and your whānau by securing large items and keeping smaller valuables safe.

Find a local builder

Search for a building professional on the Licensed Building Practitioners register.